LITTLE ROCK (AP) — Arkansas is trying to overturn 40 years of court precedent that abortion is legal until the point a fetus can live outside the womb, opponents of a state law that would ban the procedure 12 weeks into a pregnancy argued Thursday.

Groups suing on behalf of two Little Rock doctors who perform abortions asked the 8th U.S. Circuit Court of Appeals to uphold a federal judge's ruling that the ban is unconstitutional. The American Civil Liberties Union and the Center for Reproductive Rights sued the state on behalf of the doctors.

Attorney General Dustin McDaniel in April appealed Wright's ruling, which said the abortion prohibition was unconstitutional and violated the 1973 Roe v. Wade decision that legalized abortion until a fetus could viably survive outside the womb. A fetus is generally considered viable at 22 to 24 weeks.

The groups said the state was trying to overturn that court's precedent by defending the ban.

"For more than 40 years, the Supreme Court has repeatedly held that, before viability, states lack the power to ban abortion and wrest from a woman the ultimate decision of whether to continue a pregnancy_regardless of the particular interests asserted by the state, and regardless of whether the state includes exceptions to the ban," the groups said in a document setting out their argument. "This Court does not have the authority to overturn this precedent, and the state's arguments to the contrary should be roundly rejected."

By approving the 12-week ban, the Arkansas Legislature had adopted the nation's toughest abortion law last March. Two weeks later, North Dakota lawmakers passed a bill restricting abortions at six weeks — or before some women would know they're pregnant. That law is also on hold.

Legislators last year also passed a separate ban at 20 weeks, based on the assertion from abortion opponents that a fetus can feel pain by then and therefore deserves protection from abortion. But the American College of Obstetricians and Gynecologists says it knows of no legitimate evidence that shows a fetus can experience pain.

It's unclear when the appeals court will rule in the case. Both the state and opponents of the law have said they don't want oral arguments before the appeals court.